Drafting apparatus



Dec. 6, 1949 w. H. MURPHY 2,490,315

DRAFTING APPARATUS Filed Sept. 25, 1944 f- A @.1 u iwf/7 1 Patented Dec. 6, 1949 DRAFTING APPARATUS William Henry Murphy, Chicago, Ill., assignor,

by mesne assignments, to Engineering Manufacturing Co., Sheboygan, Wis., a.v corporation of Wisconsin Application September 25, 1944, Serial No. 555,609

s Claims. (ol. srl-s0) j Y This invention relates to improvements in drafting apparatus.

One object of the invention is to provide a movable or mobile parallel straight-edge construction that facilitates adjustment of a drafting blade thereof into or out of parallelism with a selected base line, for example.

Another object of the invention is to provide improvements that enable adjustment of a straight edge relative to parallel-guiding means of drafting apparatus, whereby the straight edge can be indexed or adjusted readily with respect to a selected baseline of a drawing, thereby avoiding the frequently more troublesome task involved in adjusting such a line of a drawing into registration with the straight edge of such drafting apparatus.

An additional object of the invention is to provide means for effecting a fine angular adjustment of a guided straight edge of drafting apparatus, said adjusting means having an angle indicating scale or the like associated therewith, if desired.

Other objects of the invention relate to various features of construction and arrangement of parts which will be apparent from a consideration of the following specification and accompanying drawings wherein Figure 1 is a top plan view of drafting apparatus including a .drafting board or table and guided straight edge embodying adjusting means that are illustrative of the present invention.

Fig. 2 is an enlarged broken top plan view of an end portion of the straight edge and associated adjusting means shown in Fig. 1;

Fig. 3 is a side elevation of the structure shown in Fig. 2;

Fig. 4 is a broken top plan view of a straight edge provided with a modified form of adjusting means;

Fig. 5 is a view similar to Fig. 4 but showing the straight edge in an exaggerated position of angular adjustment relative to the associated guiding means;

' straight edge and associated carriage provided with means for effecting fine angular adjustj ments of the straight edge.

Referring to the drawings, numeral I0 indicates generally, a conventional drafting board or table,

' over the upper surface of which a straight edge l I positions by means of conventional guiding apv paratus. The guiding means shown comprises a cable I2 which passes around pulleys l5, I6 at the lower edgeof the board, and pulleys Il, I8 adjacent the upper edge. The cable I2 is secured to carriages indicated generally by the numerals I9, to whichcarriages the ends of the straight edge II are attached. The cable referred to and the pulleys are mounted on the lower surface of the drafting board while the carriages or brackets I9 are disposed at opposite side edges of the board and serve to maintain the straight edge in a position constantly parallel with a given line as the straight edge is moved forwardly or rearwardly over the surface of the board or rather, over the surface of a drawing sheet attached to the board. In Fig. 1 of the drawing a conventional slack adjuster 20 is shown for tensioning cable I2,

As viewed in Figs. 2 and 3, each carriage I9 is in the form of a metal bracket, having a lower inwardly directed flange 2|, which constitutes a clip within which the cable I2 is firmly clamped against slippage. The vertical portions 22 of the carriages I9 project upwardly along the parallel side edges of the drafting board I0 and each spans between or connects one of the flanges 2I with an upper inwardly turned flange 23. The ends of the straight edge are attached to opposed anges 23 at opposite margins of the board I0.

The means for attaching the straight edgeA to the flanges 23 of the carriages are, in accordance with the present invention, of such character as to provide for angular adjustment of the straight edge as distinguished from attaching means commonly employed which retain the straight edge in a relatively fixed position of parallelism with respect to a given line. The attaching means shown in Figs. 1, 2, and 3, best illustrated in Figs. 2 and 3, comprises a stud 24 secured at each end of the straight edge and received within a threaded recess in a thumb nut 25. The stud shown in Figs. 2 and 3 passes upwardly through an arcuate slot 26 provided in the respective flange 23. The radius upon which the slot 26 is generated, corresponds generally to the distance between the stwo studs 24 or, generally, to the width ofthe drafting board or the length of the straight edge. By reason of the construction described the straight edge can be adjusted angularly upon the carriages, the carriages remaining attached to the cable I2. Such adjustment of the straight edgev with respect to the carriages, or with respect to a given line can be effected by loosening the nut 25 at the right hand end in Fig. l and slightly loosening the opposite nut 25 also. The straight edge II can then be swung angularly about the left hand stud as a pivot from the full line to the dotted line position shown in Fig. 1. The range of angular adjustment in swinging about one stud as a pivot is limited by the length of the slot at the swinging end of the straight edge, but such range is increased by the provision of two such slots, one in each carriage, as will be obvious. However, it will be understood that but one slot need be employed in utilizing the principle of the present improvements, since instead of a slot in one of the brackets. a cylindrical opening only may be employed for receiving the corresponding stud as a pivot.

With the improvements described, a draftsman, after mounting a drawing on the board with a given base line approximately parallel to the straight edge, can readily adjust the straight edge into precise parallelism with saidv linev and thereafter, during movement of the straight edge across the face oi the board, the straight edge maintains parallelism with said line. Such arrangement is a substantial convenience wheredrawings are placed upon a drafting board for additions or for corrections, since generally it is simpler tol make a precise adjustment of the straight edge with respect to a given line on a drawing than to adjust a drawing with respect to the straight edge and thereafter attach the drawing to the board to obtain the same relative positioning.

A modined structure illustrative or the invention is shown in rigs. 4 to 6 inclusive. In Fig. 6 a carriage for a straight edgeis indicated generally by the numeral 21 and is shown with the lower nange 28, to which al cable I2, similar to the above described cable, andlocated at the rear of board I0, is similarly attached- The carriage z'l is provided with` an upper ange 29 shown as overlying the adjacent upper marginal portion of the board. The adjacent end of the straight edge 30 is pivotally attachedby means of a pin 3|, to a disc or otner member 32l which carries a stud 33, about which the disc is pivotally movable through` a limited arc. TheV stud 33 extends upwardly through an aperture 34-v in the flange 29 and is provided. at its upper threaded end with a clampv nut 3,5. Upon loosening the nut 3J, the disc 3 2 isfree for limited swinging movement about the, stud 3| as, a pivot and hence the adjacent edge of the straight edge 30, being pivotally. attached by pin 3| to an off-center portion. of the disccan beE swung arcuately or adjusted, angllllllyl about a 'pivotal connection with a. second carriage, at the other end of the straight edge.l Such. pivotal movement may of course be afforded by a carriage and clamp construction similarl` to, the structure shown in Fig. 6. Where acarriage construction similar to that shown, in Fig. 651s employed at each end of the straight edge, small angular adjustment of the latter can. be eiected by loosening only the nut 35 at the end; 0fr the straight edge that is to be swung, At the opposite end, the pin 3| forms a pivot about which the straight edge swings as it is being adjusted into a selected angular position, although angular adjustments in opposite directions maybe made at both ends of the straight edgerequired.

The modication illustr-atedv in- Fig. '7V isgenerally similar to that shown in Figs.'1 to 3 inclusive and comprises a carriage 36 provided with an arcuate slot 31 within which a stud 38 carried by the adjacent, end of a straight edge may be moved. On the upper surface ofI the Mrriage 36 is an internally threaded member 39 having a flat apertured end through which the stud 38 passes. An upturned flange 40, shown integral with the carriage 36, has an aperture through which loosely passes an adjusting screw 4|, which is received within the threaded barrel portion 42 of the member 39. Stops 43 are shown secured to the screw shank on adjacent sides of the ange 40 to prevent longitudinal movement of the screw with respect to the ange. The outer end of the screw 4| is provided with the small knob 44 for convenience in rotating the screw whereby, when clamp nut 45 carried by the stud 38 has been loosened, rotation of the screw 4| will effect adjustment of the stud 38 along the slot 31 in one direction or the other, depending upon the direction of rotation of the screw. Such movement of the stud 38 eiects angular adjustment of the straight edge as in the above described modifications of the invention, but by means of the screw adjustment shown in Fig. 7 a very line or micrometric angular adjustment ofA the straight edge can be effected readily.

While a clamp nut 45 is shown in Fig. 7, similar to the corresponding elements shown inthe preceding gures, it will be apparent that after making an adjustment of the straight edge by rotation of the screw 4|, it is not essential that the nut 45 be turned down to eiect a clamping action of the corresponding end of the straight edge to the carriage as in, the preceding described structure, since the adjusting screw 4| will retain the stlaight edge in the adjusted relation. However, the use of the clamp. nut 45 is preferred.

In Fig. 7 a scale- 46 is shown on the upper surface of the carriage 36 and associatedwith the scale isa pointer 4l attached to orintegral with the end of member 39 which pointermoves with the adjacent end of the straight edgewhen the same is being adjusted by operation of the screw 4|. The graduations of the scale1 preferably indicate degrees of arcor fractions, thereof. and deviation of the pointer 4l,v from the central zero point 48 indicates the extent ofangular adjustment of the straight edge to one side, or the other of a given'base line.

While structures illustrative of the invention have been shown and, described, it will` beapparent that variations of such, structures may be utilized within the spirit of theV invention and the scope ofl the appended claims.,

I claim:

1. In combination, a drafting board, movable members comprising; separate carriages mounted for reciprocable but nonpivotable movement in unison along opposed portions of the bpaid; i`,o r guiding a straight edge over the drafting, surface of the board into successive parallel positions, said carriages comprising flanges provided with arcuate slots therein, and releasable means for clamping each end of the straight edge. to one of said anges comprising movable members movably adjustable within the respective slots for varying the angular relationship of, the straight edge with respect to a given line.

2. In combination, a drafting board, movable members comprising independent carriages mounted for reciprocable but nonpivotable movement in unison along opposed portions of the board for guiding a, straight4 edge over. the drafting surface of' the board into succeSSiYe parallel positions, said carriages comprising flanges provided with arcuate slots generated therein about aradius corresponding inl length to the distance between the slots, and releasable clamping means at each end of the straight edge releasably clamping the same to one of said anges, said means each comprising a movable threaded member which can be adjustably positioned Within the respective slot for varying the angular relationship of the straight edge with respect to a given line.

3. In combination, a drafting board, movable guiding means for a straight edge, arcuately slotted separate carriages secured to said guiding means and movable thereby in unison along opposed portions of the board for guiding a straight edge over the drafting surface of the board into successive parallel positions, said carriages being mounted for reciprocable but not pivotable movement along said board, a straight edge, and means securing the ends of the straight edge to said carriages and comprising threaded clamping members having portions operable within the arcuate slots of said carriages for varying the angular position of the straight edge with respect to a given line. WILLIAM HENRY MURPHY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

